Magnetic detection device and method for manufacturing the same

ABSTRACT

A Z detection unit includes magnetoresistive elements provided on inclined side surfaces of Z detection recesses. An X detection unit includes magnetoresistive elements provided on inclined side surfaces of X detection recesses. A Y detection unit includes magnetoresistive elements provided on inclined side surfaces of Y detection recesses. Directions of fixed magnetization of fixed magnetic layers included in the magnetoresistive elements are set to directions shown by arrows with solid lines.

CLAIM OF PRIORITY

This application is a Continuation of International Application No.PCT/JP2016/085921 filed on Dec. 2, 2016, which claims benefit ofJapanese Patent Application No. 2015-236855 filed on Dec. 3, 2015. Theentire contents of each application noted above are hereby incorporatedby reference.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates to a magnetic detection device includingmagnetoresistive elements disposed on inclined side surfaces of recessesformed in a substrate and a method for manufacturing the magneticdetection device.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 2009-20092(hereinafter referred to as Patent Document 1) describes an inventionrelating to a magnetic sensor including a substrate having grooves anddetection units formed on inclined surfaces of the grooves.

In this magnetic sensor, a silicon wafer having a (100) crystal plane isetched to form grooves having inclined side surfaces along (111) crystalplanes. A pair of detection units are formed on the same inclinedsurface of one of the grooves, and fixed resistors are formed on otherinclined surfaces. The detection units and the fixed resistors form abridge circuit. Each detection unit is formed so that the direction ofmagnetic sensitivity is the depth direction of the inclined surface.

Japanese Unexamined Patent Application Publication No. 2007-235051(hereinafter referred to as Patent Document 2) describesmagnetoresistive elements, such as TMR or GMR elements, formed oninclined surfaces of a recess formed by etching a silicon substrate.

Each magnetoresistive element includes a PIN layer and a soft layer.After the magnetoresistive element is formed on the silicon substrate,annealing is performed while a magnetic field is applied in a directionperpendicular to a substrate surface of the silicon substrate, so thatthe magnetization direction of the PIN layer is oriented in a depthdirection of the recess.

In the magnetic sensor described in Patent Document 1, the pair ofdetection units are formed on the same inclined surface of one of thegrooves in the substrate. Accordingly, the pair of detection units havethe same sensitivity polarity with respect to an external magneticfield, and therefore each detection unit needs to be connected to acorresponding one of the fixed resistors in series to form the bridgecircuit. Since the fixed resistors do not react to an external magneticfield, a magnetic detection output from the bridge circuit has a limitedsensitivity.

According to Patent Document 2, the magnetoresistive elements formed onopposing inclined surfaces are annealed while a magnetic field isapplied in a direction perpendicular to the substrate surface of thesilicon substrate, so that the PIN layers included in themagnetoresistive elements are magnetized upward in the depth directionof the inclined surfaces. Accordingly, the magnetoresistive elementsformed on the opposing inclined surfaces have resistances of oppositepolarities.

However, the invention of Patent Document 2 only describes how toproduce the magnetoresistive elements, and does not refer to a detectioncircuit formed by using the magnetoresistive elements.

In addition, according to Patent Document 2, the magnetoresistiveelements are annealed in a magnetic field directed upward with respectto the substrate surface of the silicon substrate to fix themagnetization direction of the PIN layers. Therefore, the PIN layers ofall of the magnetoresistive elements are magnetized so that themagnetization direction thereof is fixed to an upward direction, andonly a limited type of magnetoresistive elements can be formed. In otherwords, when annealing is performed in a magnetic field to fix themagnetization direction of the PIN layers, it is difficult to formmagnetoresistive elements having different sensitivity axes on the samesubstrate.

SUMMARY OF THE INVENTION

The present invention solves the above-described problems of the relatedart, and provides a magnetic detection device capable of accuratelydetecting magnetic fields in different directions by usingmagnetoresistive elements provided on inclined side surfaces of asubstrate, and a method for manufacturing the magnetic detection device.

According to the present invention, a magnetic detection device includesa substrate having recesses and magnetoresistive elements provided oninclined side surfaces of the recesses. The recesses each include afirst inclined side surface and a second inclined side surface opposingeach other with a distance therebetween gradually increasing toward asubstrate surface, the first inclined side surface and the secondinclined side surface having the magnetoresistive elements providedthereon. The magnetoresistive elements each include a fixed magneticlayer, a free magnetic layer, and a nonmagnetic intermediate layerformed between the fixed magnetic layer and the free magnetic layer. Thefixed magnetic layer has a self-pinned structure including a firstferromagnetic layer, a second ferromagnetic layer in contact with thenonmagnetic intermediate layer, and an intermediate layer disposedbetween the ferromagnetic layers, the first ferromagnetic layer and thesecond ferromagnetic layer having magnetization directions fixed toantiparallel directions. The magnetoresistive elements each have asensitivity axis determined by the magnetization direction of the secondferromagnetic layer, the sensitivity axis extending along acorresponding one of the inclined side surfaces obliquely to a thicknessdirection of the substrate. A bridge circuit is formed by connecting twoelement lines in parallel, each element line being formed by connectingin series two of the magnetoresistive elements having the sensitivityaxes oriented toward opposite sides in the thickness direction of thesubstrate.

In the magnetic detection device according to the present invention, themagnetization directions of the first ferromagnetic layer and the secondferromagnetic layer of the fixed magnetic layer may be set by layerformation in a magnetic field.

In the magnetic detection device according to the present invention, forexample, the recesses may include Z detection recesses disposed at leastat two locations on the substrate, and the bridge circuit may detect amagnetic field in a Z direction, the Z direction being the thicknessdirection of the substrate.

In this case, in each of the Z detection recesses, the sensitivity axisof the magnetoresistive element provided on the first inclined sidesurface and the sensitivity axis of the magnetoresistive elementprovided on the second inclined side surface may be oriented toward theopposite sides in the thickness direction of the substrate.

Alternatively, the Z detection recesses may include a Z detection recessin which the sensitivity axes of the magnetoresistive elements providedon the first inclined side surface and the second inclined side surfaceare both oriented downward in the thickness direction of the substrateand a Z detection recess in which the sensitivity axes of themagnetoresistive elements provided on the first inclined side surfaceand the second inclined side surface are both oriented upward in thethickness direction of the substrate. The magnetoresistive elementsprovided on the first inclined side surfaces of different ones of the Zdetection recesses and having the sensitivity axes oriented toward theopposite sides are connected in series to form a first element line. Themagnetoresistive elements provided on the second inclined side surfacesof different ones of the Z detection recesses and having the sensitivityaxes oriented toward the opposite sides are connected in series to forma second element line. The first element line and the second elementline are connected in parallel to form the bridge circuit.

In the magnetic detection device according to the present invention, therecesses may include horizontal detection recesses disposed at least attwo locations in addition to the Z detection recesses. A bridge circuitis formed by connecting two element lines in parallel, each element linebeing formed by connecting in series two of the magnetoresistiveelements provided in the horizontal detection recesses and having thesensitivity axes oriented toward opposite sides along the substratesurface. The bridge circuit detects a magnetic field in a directionparallel to the substrate surface.

For example, in each of the horizontal detection recesses, thesensitivity axis of the magnetoresistive element provided on the firstinclined side surface and the sensitivity axis of the magnetoresistiveelement provided on the second inclined side surface may be orientedtoward the opposite sides along substrate surface.

Alternatively, in each of the horizontal detection recesses, thesensitivity axis of the magnetoresistive element provided on the firstinclined side surface and the sensitivity axis of the magnetoresistiveelement provided on the second inclined side surface may be orientedtoward the same side along the substrate surface. The sensitivity axesof the magnetoresistive elements provided in different ones of thehorizontal detection recesses may be oriented toward the opposite sidesalong the substrate surface. The magnetoresistive elements provided onthe first inclined side surfaces of different ones of the horizontaldetection recesses and having the sensitivity axes oriented toward theopposite sides are connected in series to form a first element line. Themagnetoresistive elements provided on the second inclined side surfacesof different ones of the horizontal detection recesses and having thesensitivity axes oriented toward the opposite sides are connected inseries to form a second element line. The first element line and thesecond element line are connected in parallel to form the bridgecircuit.

In the magnetic detection device according to the present invention, thehorizontal detection recesses may include X detection recesses disposedat least at two locations on the substrate to detect a magnetic field inan X direction and Y detection recesses disposed at least at twolocations on the substrate to detect a magnetic field in a Y direction,the X and Y directions being perpendicular to each other.

According to the present invention, a method for manufacturing amagnetic detection device including a substrate having recesses andmagnetoresistive elements provided on inclined side surfaces of therecesses includes forming the recesses in the substrate, each recessincluding a first inclined side surface and a second inclined sidesurface opposing each other with a distance therebetween graduallyincreasing toward a substrate surface; and forming the magnetoresistiveelements on the first inclined side surface and the second inclined sidesurface of each recess, each magnetoresistive element including a fixedmagnetic layer, a free magnetic layer, and a nonmagnetic intermediatelayer formed between the fixed magnetic layer and the free magneticlayer. The fixed magnetic layer has a self-pinned structure including afirst ferromagnetic layer, a second ferromagnetic layer in contact withthe nonmagnetic intermediate layer, and an intermediate layer disposedbetween the ferromagnetic layers, the first ferromagnetic layer and thesecond ferromagnetic layer having magnetization directions fixed toantiparallel directions by layer formation in a magnetic field. Themagnetoresistive elements each have a sensitivity axis determined by themagnetization direction of the second ferromagnetic layer, thesensitivity axis extending along a corresponding one of the inclinedside surfaces obliquely to a thickness direction of the substrate. Abridge circuit is formed by connecting two element lines in parallel,each element line being formed by connecting in series two of themagnetoresistive elements having the sensitivity axes oriented towardopposite sides in the thickness direction of the substrate.

In the method for manufacturing the magnetic detection device accordingto the present invention, the recesses may include Z detection recessesformed at least at two locations on the substrate, the magnetoresistiveelements provided in the Z detection recesses having the sensitivityaxes oriented toward different sides in the thickness direction of thesubstrate. The magnetoresistive elements having the sensitivity axesoriented toward opposite sides in the thickness direction are connectedin series to form the element lines. The bridge circuit is capable ofdetecting a magnetic field in a Z direction, the Z direction being thethickness direction of the substrate.

In addition, in the method for manufacturing the magnetic detectiondevice according to the present invention, the recesses may includehorizontal detection recesses formed at least at two locations on thesubstrate in addition to the Z detection recesses, and themagnetoresistive elements provided in the horizontal detection recessesmay have the sensitivity axes oriented toward different sides along thesubstrate surface. The magnetoresistive elements having the sensitivityaxes oriented toward opposite sides are connected in series to form theelement lines. The bridge circuit is capable of detecting a magneticfield in a horizontal direction along the substrate surface of thesubstrate.

In the method for manufacturing the magnetic detection device accordingto the present invention, the horizontal detection recesses may includeX detection recesses disposed at least at two locations on the substrateto detect a magnetic field in an X direction and Y detection recessesdisposed at least at two locations on the substrate to detect a magneticfield in a Y direction, the X and Y directions being perpendicular toeach other.

In the magnetic detection device according to the present invention, themagnetoresistive elements are provided on both the first inclined sidesurface and the second inclined side surface that oppose other in eachof the recesses formed in the substrate. The magnetoresistive elementsprovided on the opposing inclined side surfaces each have thesensitivity axis determined by the direction of fixed magnetization ofthe fixed magnetic layer and extending along the corresponding inclinedside surface obliquely to the thickness direction of the substrate. Abridge circuit capable of outputting a high-sensitivity magneticdetection output can be obtained by connecting two element lines whichare each formed by connecting in series two of the magnetoresistiveelements having the sensitivity axes oriented in opposite directions.

According to the present invention, the fixed magnetic layer has theself-pinned structure in which the intermediate layer is disposedbetween the first ferromagnetic layer and the second ferromagneticlayer. At least one of the first ferromagnetic layer and the secondferromagnetic layer is formed in a magnetic field to set the sensitivityaxis determined by the direction of fixed magnetization of the secondferromagnetic layer. By forming the fixed magnetic layer in a magneticfield and fixing the direction of fixed magnetization, themagnetoresistive elements having sensitivity axes oriented towarddifferent sides can be formed on the same substrate. As a result, a Zdetection unit, an X detection unit, and a Y detection unit can beformed on the same substrate.

The magnetoresistive elements having sensitivity axes oriented towarddifferent sides can all be formed on the inclined side surfaces bysetting the direction of fixed magnetization of the magnetoresistiveelements provided on the first inclined side surfaces and that of themagnetoresistive elements provided on the second inclined side surfacesto directions oriented toward opposite sides in the thickness directionof the substrate or to directions oriented toward the same side in thethickness direction of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating the overall structure of amagnetic detection device according to embodiments of the presentinvention;

FIG. 2A illustrates a Z detection unit according to a first embodimentincluded in the magnetic detection device illustrated in FIG. 1, FIG. 2Billustrates an X detection unit according to the first embodiment, andFIG. 2C illustrates a Y detection unit according to the firstembodiment;

FIG. 3A is a sectional view of the Z detection unit illustrated in FIG.2A taken along line IIIA-IIIA, and FIG. 3B is a sectional view of the Xdetection unit illustrated in FIG. 2B taken along line IIIB-IIIB;

FIGS. 4A and 4B are enlarged sectional views illustrating layerstructures of magnetoresistive elements included in the magneticdetection device illustrated in FIGS. 2A to 2C and FIGS. 3A and 3B;

FIG. 5A illustrates a Z detection unit according to a second embodimentof the present invention, FIG. 5B illustrates an X detection unitaccording to the second embodiment, and FIG. 5C illustrates a Ydetection unit according to the second embodiment;

FIG. 6A is a sectional view of the Z detection unit illustrated in FIG.5A taken along line VIA-VIA, and FIG. 6B is a sectional view of the Xdetection unit illustrated in FIG. 5B taken along line VIB-VIB;

FIG. 7A illustrates a Z detection unit according to a modification ofthe first embodiment included in the magnetic detection deviceillustrated in FIG. 1, FIG. 7B illustrates the X detection unitaccording to the first embodiment, and FIG. 7C illustrates the Ydetection unit according to the first embodiment;

FIG. 8A illustrates a Z detection unit according to a third embodimentof the present invention, FIG. 8B illustrates an X detection unitaccording to the third embodiment, and FIG. 8C illustrates a Y detectionunit according to the third embodiment;

FIG. 9 is an enlarged sectional view illustrating a layer structure ofmagnetoresistive elements included in the magnetic detection deviceillustrated in FIGS. 5A to 5C and FIGS. 6A and 6B;

FIG. 10A is a circuit diagram of a bridge circuit for Z axis detection,FIG. 10B is a circuit diagram of a bridge circuit for X axis detection,and FIG. 10C is a circuit diagram of a bridge circuit for Y axisdetection; and

FIGS. 11A, 11B, and 11C are enlarged sectional views of a recess formedin a substrate by different processes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a magnetic detection device 1 according toembodiments of the present invention.

The magnetic detection device 1 includes a substrate 2. A Z detectionunit 10, X detection units 20, and Y detection units 30 are provided ona mounting surface (substrate surface) 3 of the substrate 2.

The Z detection unit 10 detects a magnetic field in a Z direction thatis perpendicular to the mounting surface 3 of the substrate 2. Referringto FIG. 2A, which illustrates a first embodiment, the Z detection unit10 includes at least two Z detection recesses 11A and 11B. Each Xdetection unit 20 detect a magnetic field in an X direction that isparallel to the mounting surface 3 of the substrate 2. As illustrated inFIG. 2B, each X detection unit 20 includes at least two X detectionrecesses 21A and 21B. Each Y detection unit 30 detects a magnetic fieldin a Y direction that is parallel to the mounting surface 3 of thesubstrate 2. As illustrated in FIG. 2C, each Y detection unit 30includes at least two Y detection recesses 31A and 31B.

The X detection unit 20 and the Y detection unit 30 serve as horizontaldetection units that detect magnetic fields in directions parallel tothe mounting surface 3, and the X detection recesses 21A and 21B and theY detection recesses 31A and 31B serve as horizontal detection recesses.

As illustrated in FIG. 2A, the Z detection recesses 11A and 11B eachinclude a bottom surface 12, a first inclined side surface 13 at an X1side, a second inclined side surface 14 at an X2 side, and inclined sidesurfaces 15 and 16 that oppose each other in the Y direction. The firstinclined side surface 13 and the second inclined side surface 14 opposeeach other in the X direction, and the distance therebetween is smalleston the bottom surface 12 and gradually increases toward the mountingsurface 3.

Referring to FIGS. 3A and 11A, the substrate 2 that is used is a silicon(Si) substrate, and the mounting surface 3 thereof has a (100) planeorientation. Recesses which each have the first inclined side surface13, the second inclined side surface 14, and two other inclined sidesurfaces 15 and 16 along (111) planes are formed by anisotropicallyetching the mounting surface 3 of the substrate 2 with an etchant aftercovering the mounting surface 3 with a layer of silicon oxide (SiO₂) orthe like over regions other than regions in which the Z detectionrecesses 11A and 11B are to be formed. The inclined side surfaces 13,14, 15, and 16 are at an angle θ of about 55 degrees with respect to ahorizontal plane.

FIGS. 11B and 11C illustrate other methods for processing the substrate2. FIG. 11B illustrates a processing method in which the substrate 2 isformed by stacking a P-type silicon substrate with a (100) planeorientation on an N-type silicon substrate with a (100) planeorientation, and is electrochemically etched. In the electrochemicaletching process, a surface of the N-type silicon substrate serves as anetching stopper surface. Accordingly, the first inclined side surface 13and the second inclined side surface 14 in each of the Z detectionrecesses 11A and 11B can be accurately formed to have a uniformdimension in the thickness direction (Z direction).

FIG. 11C illustrates a processing method in which the substrate 2 isformed by stacking an N-type silicon substrate with a (100) planeorientation on a P-type silicon substrate with a (100) planeorientation, and is etched by a pulsed current anodization method. Inthis processing method, a surface of the P-type silicon substrate servesas an etching stopper surface. Also in this case, the first inclinedside surface 13 and the second inclined side surface 14 can beaccurately formed to have a uniform dimension in the thickness direction(Z direction).

As illustrated in FIG. 2B, the X detection recesses 21A and 21B, whichare horizontal detection recesses, have an elongated rectangular shapewith a length in the Y direction greater than a width in the Xdirection. As illustrated in FIG. 3B, the X detection recesses 21A and21B each have a first inclined side surface 23 at the X1 side and asecond inclined side surface 24 at the X2 side. The distance between thefirst inclined side surface 23 and the second inclined side surface 24in the X direction is smallest on a bottom surface 22, and graduallyincreases toward the mounting surface 3. As illustrated in FIG. 2B, theX detection recesses 21A and 21B each have inclined side surfaces 25 and26 that oppose each other in the Y direction.

The X detection recesses 21A and 21B are formed by the same method asthe method for forming the Z detection recesses 11A and 11B, and any ofthe etching methods illustrated in FIGS. 11A, 11B, and 11C may be used.

As illustrated in FIG. 2C, the Y detection recesses 31A and 31B, whichare horizontal detection recesses, have an elongated rectangular shapewith a length in the X direction greater than a width in the Ydirection. The Y detection recesses 31A and 31B each have a bottomsurface 32, a first inclined side surface 33 at a Y1 side, and a secondinclined side surface 34 at a Y2 side. The distance between the firstinclined side surface 33 and the second inclined side surface 34 in theY direction is smallest on the bottom surface 32, and graduallyincreases toward the mounting surface 3. The Y detection recesses 31Aand 31B each have inclined side surfaces 35 and 36 that oppose eachother in the X direction.

The Y detection recesses 31A and 31B are formed by the same method asthe method for forming the Z detection recesses 11A and 11B, and any ofthe etching methods illustrated in FIGS. 11A, 11B, and 11C may be used.

As illustrated in FIGS. 2A and 3A, a first magnetoresistive element 40(R1) is provided on the first inclined side surface 13 of the Zdetection recess 11A, and a second magnetoresistive element 40 (R2) isprovided on the second inclined side surface 14 of the Z detectionrecess 11A. A fourth magnetoresistive element 40 (R4) is provided on thefirst inclined side surface 13 of the Z detection recess 11B, and athird magnetoresistive element 40 (R3) is provided on the secondinclined side surface 14 of the Z detection recess 11B.

The magnetoresistive elements 40 (R1, R2, R3, and R4) are GMR elements(giant magnetoresistive elements) having the same structure. FIGS. 4Aand 4B illustrate multilayer structures of the magnetoresistive elements40.

The magnetoresistive element 40 illustrated in FIG. 4A is produced byforming a seed layer 42 made of Ni—Fe—Cr on the surface of the substrate2 and then forming a fixed magnetic layer having a three-layerself-pinned structure on the seed layer 42 by successively forming afirst ferromagnetic layer 43 made of Co—Fe, an intermediate layer 44made of Ru, and a second ferromagnetic layer 45 made of Co—Fe.

Referring to FIG. 3A, when the magnetoresistive elements 40 (R1, R2, R3,R4) of the Z detection unit 10 are formed, the first ferromagnetic layer43 is formed while a magnetic field Bx in an X-axis direction (X2direction) is applied. Then, after the intermediate layer 44 is formed,the second ferromagnetic layer 45 is formed while a magnetic field Bx inan X-axis direction (X1 direction) opposite to that in the process offorming the first ferromagnetic layer 43 is applied.

When the thickness of the intermediate layer 44 made of Ru isappropriately set, the magnetization direction of the firstferromagnetic layer 43 is fixed to the X2 direction, and themagnetization direction of the second ferromagnetic layer 45 is fixed tothe X1 direction. The magnetization direction of the secondferromagnetic layer 45 serves as the direction of fixed magnetization(P). In FIGS. 2A to 2C and FIGS. 3A and 3B, the directions of fixedmagnetization (P) are shown by the arrows with solid lines.

The first ferromagnetic layer 43 may be formed as a high-coercive-forcelayer having a coercive force higher than that of the secondferromagnetic layer 45. In such a case, if the first ferromagnetic layer43 is formed while the magnetic field Bx in the X2 direction is applied,even when the second ferromagnetic layer 45 is subsequently formed whileno magnetic field is applied or while a magnetic field in any directionis applied, the magnetization direction of the first ferromagnetic layer43 is fixed to the X2 direction and the magnetization direction of thesecond ferromagnetic layer 45 is fixed to the X1 direction.

After the fixed magnetic layer having the three-layer structureincluding the first ferromagnetic layer 43, the intermediate layer 44,and the second ferromagnetic layer 45 is formed, a nonmagneticintermediate layer 46 made of Cu is formed on the second ferromagneticlayer 45, and a free magnetic layer 47 having a two-layer structureincluding a Co—Fe layer and a Ni—Fe layer is formed on the nonmagneticintermediate layer 46. Then, the top surface is covered with a cap layer48 made of Ta.

After the layers illustrated in FIG. 4A are formed, etching is performedso that only the magnetoresistive elements 40 (R1, R2, R3, and R4)remain and the multilayer body is removed in other regions.

The magnetoresistive element 40 illustrated in FIG. 4B is produced byforming a free magnetic layer 47 and a nonmagnetic intermediate layer 46on a seed layer 42, and then forming a fixed magnetic layer having athree-layer self-pinned structure.

The fixed magnetic layer illustrated in FIG. 4B is formed bysuccessively forming a second ferromagnetic layer 45, an intermediatelayer 44, and a first ferromagnetic layer 43 on the nonmagneticintermediate layer 46. When the first ferromagnetic layer 43 is formedin a magnetic field so that the magnetization direction thereof is setto the X2 direction, the magnetization direction of the secondferromagnetic layer 45 is fixed to the X1 direction due tocross-coupling (anti-parallel coupling) across the intermediate layer44. Accordingly, the direction of fixed magnetization (P), which is thedirection of a sensitivity axis, is set to the X1 direction.

For example, the second ferromagnetic layer 45 is formed while nomagnetic field is applied or while a magnetic field in any direction isapplied. Then, after the intermediate layer 44 is formed, the firstferromagnetic layer 43 is formed while a magnetic field in the X1direction is applied. The first ferromagnetic layer 43 is formed as ahigh-coercive-force layer having a coercive force higher than that ofthe second ferromagnetic layer 45. When the first ferromagnetic layer 43is gradually formed on the intermediate layer 44 while the secondferromagnetic layer 45 is magnetized in the X1 direction by a magneticfield, the first ferromagnetic layer 43 that is being formed ismagnetized in the X2 direction due to cross-coupling (anti-parallelcoupling) between the first ferromagnetic layer 43 and the secondferromagnetic layer 45. When the first ferromagnetic layer 43 iscompletely formed, the magnetization direction of the firstferromagnetic layer 43, which is a high-coercive-force layer, is fixedto the X2 direction, and the magnetization direction of the secondferromagnetic layer 45 is fixed to the X1 direction.

In the process of producing the magnetoresistive element 40 illustratedin FIG. 4B, an antiferromagnetic layer 49 a made of, for example, anIr—Mn alloy (iridium-manganese alloy) or a Pt—Mn alloy(platinum-manganese alloy) is formed on the first ferromagnetic layer43, and is then annealed while no magnetic field is applied.Accordingly, the magnetization direction of the first ferromagneticlayer 43 is strongly fixed due to exchange coupling between the firstferromagnetic layer 43, which is magnetized in the X2 direction, and theantiferromagnetic layer 49 a. As a result, the magnetization directionof the second ferromagnetic layer 45 is reliably fixed to the X1direction.

As illustrated in FIGS. 2A and 3A, the magnetoresistive elements 40included in the Z detection unit 10 are formed so that the directions offixed magnetization (P) thereof are oriented in a thickness direction ofthe substrate 2 (depth direction of the Z detection recesses 11A and11B) along the first inclined side surfaces 13 and the second inclinedside surfaces 14. The layers of the magnetoresistive elements 40 areformed while the magnetic field Bx is applied so that, in the Zdetection recess 11A, the direction of fixed magnetization (P) of thefirst magnetoresistive element 40 (R1) is fixed to a direction orientedupward from the bottom surface 12 toward the mounting surface 3, and thedirection of fixed magnetization (P) of the second magnetoresistiveelement 40 (R2) is fixed to a direction oriented downward from themounting surface 3 toward the bottom surface 12.

In the other Z detection recess 11B, the direction of fixedmagnetization (P) of the fourth magnetoresistive element 40 (R4) is thesame as that of the first magnetoresistive element 40 (R1), and thedirection of fixed magnetization (P) of the third magnetoresistiveelement 40 (R3) is the same as that of the second magnetoresistiveelement 40 (R2).

Preferably, the free magnetic layer 47 of each magnetoresistive element40 is put into a single magnetic domain state and has a uniformmagnetization direction. The free magnetic layer 47 is magnetized in auniform direction based on the shape anisotropy thereof or by being hardbiased by an external magnet. In the Z detection unit 10 illustrated inFIG. 2A, the free magnetic layers 47 of all of the magnetoresistiveelements 40 (R1, R2, R3, and R4) are magnetized so that the direction ofmagnetization (F) thereof is the Y2 direction, as shown by the arrowswith broken lines.

When an external magnetic field in the Z1 direction or the Z2 directionis applied to the Z detection unit 10, the direction of magnetization(F) of each free magnetic layer 47 is changed toward the direction ofthe external magnetic field. When the direction of magnetization (F) ofthe free magnetic layer 47 and the direction of fixed magnetization (P)of the fixed magnetic layer are oriented toward the same side, theresistance is minimized. When the direction of magnetization (F) of thefree magnetic layer 47 and the direction of fixed magnetization (P) ofthe fixed magnetic layer are oriented toward opposite sides, theresistance is maximized.

When an external magnetic field in the Z1 direction or the Z2 directionis applied to the Z detection unit 10, the resistances of the firstmagnetoresistive element 40 (R1) and the fourth magnetoresistive element40 (R4) change in the same direction, and the resistances of the secondmagnetoresistive element 40 (R2) and the third magnetoresistive element40 (R3) change in the same direction.

FIG. 10A illustrates a Z detection bridge circuit 51. In the bridgecircuit 51, the first magnetoresistive element 40 (R1) and the secondmagnetoresistive element 40 (R2) are connected in series to form a firstelement line, and the third magnetoresistive element 40 (R3) and thefourth magnetoresistive element 40 (R4) are connected to form a secondelement line. The two element lines are connected in parallel. The firstmagnetoresistive element 40 (R1) and the third magnetoresistive element40 (R3) are connected to a direct-current power supply, and the secondmagnetoresistive element 40 (R2) and the fourth magnetoresistive element40 (R4) are grounded.

In the bridge circuit 51 illustrated in FIG. 10A, the secondmagnetoresistive element 40 (R2) and the third magnetoresistive element40 (R3) may be switched.

As illustrated in FIG. 10A, a midpoint potential between the firstmagnetoresistive element 40 (R1) and the second magnetoresistive element40 (R2) and a midpoint potential between the third magnetoresistiveelement 40 (R3) and the fourth magnetoresistive element 40 (R4) areapplied to a differential amplifier 54, so that a Z-direction magneticdetection output Oz is obtained.

In the example illustrated in FIGS. 2A and 3A, when a magnetic field inthe Z1 direction is applied to the Z detection unit 10 and themagnetization direction of the free magnetic layer 47 of each of themagnetoresistive elements 40 (R1, R2, R3, and R4) is changed toward theZ1 direction, the resistances of the magnetoresistive elements 40 (R1and R4) decrease and the resistances of the magnetoresistive elements 40(R2 and R3) increase. Accordingly, the magnetic detection output Ozincreases. Conversely, when a magnetic field in the Z2 direction isapplied and the magnetization direction of the free magnetic layer 47 ofeach of the magnetoresistive elements 40 (R1, R2, R3, and R4) is changedtoward the Z2 direction, the magnetic detection output Oz decreases.

Referring to FIG. 3A, when the magnetoresistive elements 40 of the Zdetection unit 10 are formed, the fixed magnetic layers are formed whilethe magnetic field Bx in an X-axis direction is applied so that thedirection of fixed magnetization (P) of the fixed magnetic layers in themagnetoresistive elements 40 (R1 and R4) on the first inclined sidesurfaces 13 of the Z detection recesses 11A and 11B and that of thefixed magnetic layers in the magnetoresistive elements 40 (R2 and R3) onthe second inclined side surfaces 14 of the Z detection recesses 11A and11B are oriented toward opposite sides in the Z direction along theinclined side surfaces.

Therefore, when the bridge circuit 51 is formed by connecting themagnetoresistive elements 40 (R1 and R4) on the first inclined sidesurfaces 13 to the magnetoresistive elements 40 (R2 and R3) on thesecond inclined side surfaces 14 in series, a magnetic field in the Zdirection can be accurately detected.

As illustrated in FIGS. 2B and 3B, in the X detection unit 20, a fifthmagnetoresistive element 40 (R5) is provided on the first inclined sidesurface 23 of the X detection recess 21A, and a sixth magnetoresistiveelement 40 (R6) is provided on the second inclined side surface 24 ofthe X detection recess 21A. An eighth magnetoresistive element 40 (R8)is provided on the first inclined side surface 23 of the X detectionrecess 21B, and a seventh magnetoresistive element 40 (R7) is providedon the second inclined side surface 24 of the X detection recess 21B.

The layer structure of each of the magnetoresistive elements 40 (R5, R6,R7, and R8) is the same as that illustrated in FIGS. 4A and 4B.Referring to FIG. 3B, when the magnetoresistive elements 40 of the Xdetection unit 20 are formed, the first ferromagnetic layer 43 is formedwhile a magnetic field Bz in the Z2 direction is applied so that themagnetization direction thereof is fixed to a direction oriented alongthe Z2 direction, and the second ferromagnetic layer 45 is formed whilea magnetic field Bz in the Z1 direction is applied so that themagnetization direction thereof is fixed to a direction oriented upward.Therefore, as shown by the arrows with solid lines, the directions offixed magnetization (P) of the fixed magnetic layers in themagnetoresistive elements 40 (R5, R6, R7, and R8) are fixed todirections oriented upward along the inclined side surfaces 23 and 24 atan angle with respect to the thickness direction of the substrate 2.

In both of the X detection recesses 21A and 21B, the direction of fixedmagnetization (P) of the fixed magnetic layers in the magnetoresistiveelements 40 (R5 and R8) on the first inclined side surfaces 23 and thatof the fixed magnetic layers in the magnetoresistive elements 40 (R6 andR7) on the second inclined side surfaces 24 are oriented toward oppositesides in the X direction.

Therefore, when an external magnetic field in the X direction isapplied, the direction in which the resistances of the fifthmagnetoresistive element 40 (R5) and the eighth magnetoresistive element40 (R8) change is opposite to the direction in which the resistances ofthe sixth magnetoresistive element 40 (R6) and the seventhmagnetoresistive element 40 (R7) change.

As illustrated in FIG. 10B, in the X detection unit 20, themagnetoresistive elements 40 (R5, R6, R7, and R8) form an X detectionbridge circuit 52. When an external magnetic field in the X1 directionis applied to the X detection unit 20, a magnetic detection output Oxfrom a differential amplifier 55 increases. When an external magneticfield in the X2 direction is applied, the magnetic detection output Oxfrom the differential amplifier 55 decreases.

In the Y detection unit 30 illustrated in FIG. 2C, a ninthmagnetoresistive element 40 (R9) is provided on the first inclined sidesurface 33 of the Y detection recess 31A, and a tenth magnetoresistiveelement 40 (R10) is provided on the second inclined side surface 34 ofthe Y detection recess 31A. A twelfth magnetoresistive element 40 (R12)is provided on the first inclined side surface 33 of the Y detectionrecess 31B, and an eleventh magnetoresistive element 40 (R11) isprovided on the second inclined side surface 34 of the Y detectionrecess 31B.

The layer structure of each of the magnetoresistive elements 40 (R9,R10, R11, and R12) is the same as that illustrated in FIGS. 4A and 4B.Similar to the X detection unit 20, when the magnetoresistive elements40 of the Y detection unit 30 are formed, the fixed magnetic layers areformed while the magnetic field Bz is applied so that, as shown by thearrows with solid lines, the directions of fixed magnetization (P) ofthe fixed magnetic layers in the magnetoresistive elements 40 (R9, R10,R11, and R12) are fixed to directions oriented upward along the inclinedside surfaces 33 and 34 at an angle with respect to the thicknessdirection of the substrate 2.

In both of the Y detection recesses 31A and 31B, the direction of fixedmagnetization (P) of the fixed magnetic layers in the magnetoresistiveelements 40 (R9 and R12) on the first inclined side surfaces 33 and thatof the fixed magnetic layers in the magnetoresistive elements 40 (R10and R11) on the second inclined side surfaces 34 are oriented towardopposite sides in the Y direction.

Therefore, when an external magnetic field in the Y direction isapplied, the direction in which the resistances of the ninthmagnetoresistive element 40 (R9) and the twelfth magnetoresistiveelement 40 (R12) change is opposite to the direction in which theresistances of the tenth magnetoresistive element 40 (R10) and theeleventh magnetoresistive element 40 (R11) change.

As illustrated in FIG. 10C, in the Y detection unit 30, themagnetoresistive elements 40 (R9, R10, R11, and R12) form a Y detectionbridge circuit 53. When an external magnetic field in the Y1 directionis applied to the Y detection unit 30, a magnetic detection output Oyfrom a differential amplifier 56 increases. When an external magneticfield in the Y2 direction is applied, the magnetic detection output Oyfrom the differential amplifier 56 decreases.

In the magnetoresistive elements 40 (R5, R6, R7, and R8) of the Xdetection unit 20 and the magnetoresistive elements 40 (R9, R10, R11,and R12) of the Y detection unit 30, the free magnetic layers 47 aremagnetized in the Y2 direction and the X1 direction, respectively, asshown by the arrows with broken lines in FIGS. 2B and 2C, based on theshape anisotropy thereof or by, for example, hard biasing.

In the magnetic detection device 1 illustrated in FIG. 1, the Zdetection unit 10, the X detection units 20, and the Y detection units30 are formed on a single substrate 2. Therefore, magnetic fields in theZ, X, and Y directions and variations in the intensities thereof can bedetected by using a single substrate 2.

The Z detection recesses 11A and 11B of the Z detection unit 10, the Xdetection recesses 21A and 21B of each X detection unit 20, and the Ydetection recesses 31A and 31B of each Y detection unit 30 can be formedsimultaneously by etching.

When the magnetoresistive elements 40 of the Z detection unit 10 areformed, the fixed magnetic layers are formed while the magnetic field Bxis applied. When the magnetoresistive elements 40 of the X detectionunits 20 and the Y detection units 30 are formed, the fixed magneticlayers of the detection units 20 and 30 can be formed simultaneouslywhile the magnetic field Bz is applied. Thus, in each of the X detectionunits 20 and the Y detection units 30, the directions of fixedmagnetization (P) of the fixed magnetic layers can be set to directionsoriented in the thickness direction of the substrate along the inclinedside surfaces.

In the first embodiment, the Z detection unit 10, the X detection units20, and the Y detection units 30 can be formed even when magnetic fieldsare applied only in two directions when the fixed magnetic layers of themagnetoresistive elements 40 are formed.

FIGS. 5A to 5C illustrate a magnetic detection device 101 according to asecond embodiment of the present invention.

Similar to the magnetic detection device 1 according to the firstembodiment illustrated in FIGS. 2A to 2C, in this magnetic detectiondevice 101, a Z detection unit 10 includes Z detection recesses 11A and11B, each X detection unit 20 includes X detection recesses 21A and 21B,and each Y detection unit 30 includes Y detection recesses 31A and 31B.

As illustrated in FIGS. 5A and 6A, a first magnetoresistive element 50(R1) is formed on a first inclined side surface 13 of the Z detectionrecess 11A, and a second magnetoresistive element 50 (R2) is formed on asecond inclined side surface 14 of the Z detection recess 11A. Asillustrated in FIG. 5A, a fourth magnetoresistive element 50 (R4) isformed on a first inclined side surface 13 of the Z detection recess11B, and a third magnetoresistive element 50 (R3) is formed on a secondinclined side surface 14 of the Z detection recess 11B.

As illustrated in FIGS. 5B and 6B, a fifth magnetoresistive element 50(R5) is formed on a first inclined side surface 23 of the X detectionrecess 21A, and a sixth magnetoresistive element 50 (R6) is formed on asecond inclined side surface 24 of the X detection recess 21A. An eighthmagnetoresistive element 50 (R8) is formed on a first inclined sidesurface 23 of the X detection recess 21B, and a seventh magnetoresistiveelement 50 (R7) is formed on a second inclined side surface 24 of the Xdetection recess 21B.

As illustrated in FIG. 5C, a ninth magnetoresistive element 50 (R9) isformed on a first inclined side surface 33 of the Y detection recess31A, and a tenth magnetoresistive element 50 (R10) is formed on a secondinclined side surface 34 of the Y detection recess 31A. A twelfthmagnetoresistive element 50 (R12) is formed on a first inclined sidesurface 33 of the Y detection recess 31B, and an eleventhmagnetoresistive element 50 (R11) is formed on a second inclined sidesurface 34 of the Y detection recess 31B.

As illustrated in FIG. 9, similar to the magnetoresistive element 40illustrated in FIG. 4A, in each of the magnetoresistive elements 50according to the second embodiment, a ferromagnetic layer 43 made ofCo—Fe, an intermediate layer 44 made of Ru, and a second ferromagneticlayer 45 made of Co—Fe are formed on a seed layer 42 to form a fixedmagnetic layer having a three-layer self-pinned structure.

As illustrated in FIG. 6A, in the Z detection unit 10, the fixedmagnetic layers having the three-layer structure are formed while themagnetic field Bx is applied so that the directions of fixedmagnetization (P) of the fixed magnetic layers in the magnetoresistiveelements 50 (R1, R2, R3, and R4) are fixed to the directions shown bythe arrows with solid lines. As illustrated in FIG. 6B, in the Xdetection unit 20, the fixed magnetic layers having the three-layerstructure are formed while the magnetic field Bz is applied so that thedirections of fixed magnetization (P) of the fixed magnetic layers inthe magnetoresistive elements 50 (R5, R6, R7, and R8) are fixed to thedirections shown by the arrows with solid lines. Similarly, in the Ydetection unit 30, the fixed magnetic layers are formed while themagnetic field Bz is applied so that the directions of fixedmagnetization (P) of the fixed magnetic layers in the magnetoresistiveelements 50 (R9, R10, R11, and R12) are fixed to the directions shown bythe arrows with solid lines.

As illustrated in FIG. 9, after the direction of fixed magnetization (P)of the fixed magnetic layer of each magnetoresistive element 50 isfixed, a nonmagnetic intermediate layer 46 is formed on the fixedmagnetic layer, and a portion of the free magnetic layer 47 are formedon the nonmagnetic intermediate layer 46.

After that, an upper portion of the free magnetic layer 47 isadditionally formed, and an upper antiferromagnetic layer 49 b made ofIr—Mn is formed on the upper portion of the free magnetic layer 47 whilea magnetic field is applied. Since the magnetic field is applied, thefree magnetic layer 47 is put into a single magnetic domain state andmagnetized in a uniform direction due to exchange coupling between theupper antiferromagnetic layer 49 b and the free magnetic layer 47.

In the Z detection unit 10, the upper antiferromagnetic layer 49 b isformed while a magnetic field in the X1 direction is applied so that, asshown by the arrows with broken lines in FIGS. 5A and 6A, the directionof magnetization (F) of the free magnetic layer 47 is the same as thedirection of fixed magnetization (P). In the X detection unit 20 and theY detection unit 30, the upper antiferromagnetic layer 49 b is formedwhile a magnetic field in the Z1 direction is applied so that, as shownby the arrows with broken lines, the direction of magnetization (F) ofeach free magnetic layer 47 is the same as the direction of fixedmagnetization (P).

The structures of bridge circuits obtained by connecting themagnetoresistive elements in the magnetic detection device 101 accordingto the second embodiment are the same as those illustrated in FIGS. 10A,10B, and 10C.

As illustrated in FIGS. 5A to 5C and FIGS. 6A and 6B, in each of themagnetoresistive elements 50 (R1 to R12) included in the magneticdetection device 101 according to the second embodiment, the directionof fixed magnetization (P) of the fixed magnetic layer is the same asthe direction of magnetization (F) of the free magnetic layer 47 when noexternal magnetic field is applied. Therefore, the resistance of themagnetoresistive element 50 is at a minimum. When the intensity of anexternal magnetic field in a direction opposite to the direction ofmagnetization (F) of the free magnetic layer 47 is gradually increased,the direction of magnetization (F) of the free magnetic layer 47 isreversed, and the resistance of the magnetoresistive element 50 ismaximized. Thus, the magnetic detection outputs Oz, Ox, and Oy arechanged.

In the Z detection unit 10, the directions of magnetization (F) of thefree magnetic layers 47 may be opposite to the directions shown by thearrows with broken line in FIG. 6A. Similarly, also in the X detectionunit 20 and the Y detection unit 30, the directions of magnetization (F)of the free magnetic layers 47 may be opposite to the directions shownby the arrow with broken line in FIG. 6B.

As illustrated in FIG. 5A, in the magnetic detection device 101according to the second embodiment, a shield layer 61 composed of a softmagnetic material layer made of NI—Fe, for example, is formed on abottom surface 12 of each of the Z detection recesses 11A and 11B of theZ detection unit 10. Preferably, a shield layer is additionally formedon a mounting surface 3 of the substrate 2 so as to surround each of theZ detection recesses 11A and 11B. When the shield layer 61 is provided,a magnetic field in a direction other than the Z direction, which is thesensitivity direction, can be absorbed and superposition of noise on themagnetic detection output Oz due to a disturbance magnetic field can beprevented.

Similarly, in the X detection unit 20, a shield layer 62 is formed on abottom surface 22 of each of the X detection recesses 21A and 21B, and ashield layer 63 is formed on the mounting surface 3 in the regionbetween the X detection recesses 21A and 21B. The shield layers 62 and63 have an elongated shape that extends in a direction perpendicular tothe directions of fixed magnetization (P) of the fixed magnetic layersin the magnetoresistive elements 50 (R5, R6, R7, and R8). Accordingly, adisturbance magnetic field in a direction other than the X direction,which is the sensitivity direction, can be absorbed.

In the Y detection unit 30, a shield layer 64 is formed on a bottomsurface 32 of each of the Y detection recesses 31A and 31B, and a shieldlayer 65 is formed on the mounting surface 3 in the region between the Ydetection recesses 31A and 31B. The shield layers 64 and 65 have anelongated shape that extends in a direction perpendicular to thedirections of fixed magnetization (P) of the fixed magnetic layers inthe magnetoresistive elements 50 (R9, R10, R11, and R12). Accordingly, adisturbance magnetic field in a direction other than the Y direction,which is the sensitivity direction, can be absorbed.

By placing a shield layer on the bottom surface of each detectionrecess, the required shield layers can be arranged in a space-savingmanner.

FIGS. 7A to 7C illustrates a magnetic detection device la according to amodification of the first embodiment. A Z detection unit 10 aillustrated in FIG. 7A is a modification of the Z detection unit 10included in the magnetic detection device 1 illustrated in FIGS. 2A to2C. The structures of an X detection unit 20 illustrated in FIG. 7B anda Y detection unit 30 illustrated in FIG. 7C are the same as thoseillustrated in FIGS. 2B and 2C.

In the Z detection unit 10 illustrated in FIG. 2A, the Z detectionrecesses 11A and 11B have a square shape that differs from the elongatedrectangular shape of the X detection recesses 21A and 21B and the Ydetection recesses 31A and 31B. The dimensions of the magnetoresistiveelements 40 provided in the Z detection recesses 11A and 11B illustratedin FIG. 2A along the substrate surface is less than the dimensions ofthe magnetoresistive elements 40 of the X detection unit 20 illustratedin FIG. 2B and the Y detection unit 30 illustrated in FIG. 2C along thesubstrate surface.

In contrast, in the Z detection unit 10 a illustrated in FIG. 7A, theshape and dimensions of the Z detection recesses 11A and 11B are thesame as the shape and dimensions of the X detection recesses 21A and 21Band the Y detection recesses 31A and 31B. In addition, the shape anddimensions of the magnetoresistive elements 40 (R1, R2, R3, and R4)provided in the Z detection recesses 11A and 11B are the same as thoseof the magnetoresistive elements 40 (R5, R6, R7, and R8) provided in theX detection recesses 21A and 21B and the magnetoresistive elements 40(R9, R10, R11, and R12) provided in the Y detection recesses 31A and31B.

The Z detection recesses 11A and 11B in the Z detection unit 10 aillustrated in FIG. 7A can be formed so that the longitudinal directionthereof is the same as that of the X detection recesses 21A and 21B.Alternatively, the Z detection recesses 11A and 11B can be formed sothat the longitudinal direction thereof is the same as that of the Ydetection recesses 31A and 31B. In addition, all of the magnetoresistiveelements 40 can be formed in the same pattern and size. In addition, thearea of the magnetoresistive elements 40 (R1, R2, R3, and R4) includedin the Z detection unit 10 a illustrated in FIG. 7A is greater than thatof the magnetoresistive elements 40 (R1, R2, R3, and R4) included in theZ detection unit 10 illustrated in FIG. 2A. Therefore, the rate ofchange of the resistances of the magnetoresistive elements 40 (R1, R2,R3, and R4) can be increased, and the sensitivity of the Z detectionunit can be increased accordingly.

The shape and size of the Z detection unit 10, 10 a according to thepresent invention are not limited to those in the above-describedembodiments. For example, when the detection units are arranged on thesame substrate, the Z detection unit 10, 10 a may be formed so that thearea thereof is greater than that of the X detection unit 20 or the Ydetection unit 30.

FIGS. 8A to 8C illustrates a magnetic detection device 201 according toa third embodiment of the present invention.

A Z detection unit 10 b illustrated in FIG. 8A includes Z detectionrecesses 11A and 11B having the same shape and dimensions as those ofthe Z detection recesses 11A and 11B included in the Z detection unit 10illustrated in FIG. 2A. In the Z detection unit 10 b illustrated in FIG.8A, the direction of fixed magnetization (P) of a first magnetoresistiveelement 40 (R1) provided on a first inclined side surface 13 of the Zdetection recess 11A and that of a fourth magnetoresistive element 40(R4) provided on a second inclined side surface 14 of the Z detectionrecess 11A are both oriented in the Z1 direction. In addition, thedirection of fixed magnetization (P) of a second magnetoresistiveelement 40 (R2) provided on a first inclined side surface 13 of the Zdetection recess 11B and a third magnetoresistive element 40 (R3)provided on a second inclined side surface 14 of the Z detection recess11B are both oriented in the Z2 direction.

In the Z detection unit 10 b illustrated in FIG. 8A, themagnetoresistive elements 40 (R1, R2, R3, and R4) form a bridge circuit51 that is the same as that illustrated in the circuit diagram of FIG.10A. Here, the first magnetoresistive element 40 (R1) on the firstinclined side surface 13 of the Z detection recess 11A and the secondmagnetoresistive element 40 (R2) on the first inclined side surface 13of the Z detection recess 11B are connected in series to form a firstelement line. The third magnetoresistive element 40 (R3) on the secondinclined side surface 14 of the Z detection recess 11B and the fourthmagnetoresistive element 40 (R4) on the second inclined side surface 14of the Z detection recess 11A are connected in series to form a secondelement line. The first element line and the second element line areconnected in parallel to form the bridge circuit.

The Z detection recesses 11A and 11B are formed in the same etchingprocess. Therefore, the first inclined side surface 13 of the Zdetection recess 11A and the first inclined side surface 13 of the Zdetection recess 11B, which are formed along the same crystal plane, areeasily formed to have the same angle. Also, the second inclined sidesurface 14 of the Z detection recess 11A and the second inclined sidesurface 14 of the Z detection recess 11B, which are formed along thesame crystal plane, are easily formed to have the same angle.Accordingly, when the first magnetoresistive element 40 (R1) and thesecond magnetoresistive element 40 (R2) provided on the first inclinedside surfaces 13, which can be easily formed to have the same angle, areconnected in series to form the first element line and when the midpointpotential of the first element line is obtained, differences in midpointpotential of the first element line between products can be easilyreduced. Similarly, when the third magnetoresistive element 40 (R3) andthe fourth magnetoresistive element 40 (R4) provided on the secondinclined side surfaces 14, which can be easily formed to have the sameangle, are connected in series to form the second element line and whenthe midpoint potential of the second element line is obtained,differences in midpoint potential of the second element line betweenproducts can be easily reduced.

In an X detection unit 20 b illustrated in FIG. 8B, the directions offixed magnetization (P) of a fifth magnetoresistive element 40 (R5) andan eighth magnetoresistive element 40 (R8) provided on inclined sidesurfaces of an X detection recess 21A are both oriented in the X1direction. The directions of fixed magnetization (P) of a sixthmagnetoresistive element 40 (R6) and a seventh magnetoresistive element40 (R7) provided on inclined side surfaces of an X detection recess 21Bare both oriented the X2 direction. Thus, the directions of fixedmagnetization (P) of the magnetoresistive elements 40 in the X detectionrecess 21A are opposite to those of the magnetoresistive elements 40 inthe X detection recess 21B in the X direction.

Also in the X detection unit 20 b, the fifth magnetoresistive element 40(R5) and the sixth magnetoresistive element 40 (R6) provided on thefirst inclined side surfaces 23, which can be easily formed to have thesame angle, of the X detection recesses 21A and 21B are connected inseries to form a first element line. The seventh magnetoresistiveelement 40 (R7) and the eighth magnetoresistive element 40 (R8) providedon the second inclined side surfaces 24 of the X detection recesses 21Aand 21B, which can be easily formed to have the same angle, areconnected in series to form a second element line. Since themagnetoresistive elements provided on the inclined side surfaces thatcan be easily formed to have the same angle are connected in series,differences in midpoint potentials of the first element line and thesecond element line can be reduced.

The Y detection unit 30 b has a structure obtained by rotating the Xdetection unit 20 b ninety degrees along the substrate surface.Accordingly, the Y detection unit 30 b has an effect similar to that ofthe X detection unit 20 b.

In each of the above-described embodiments, the fixed magnetic layer ofeach magnetoresistive element has a self-pinned structure, and is formedwhile a magnetic field is applied. Accordingly, it is not necessary toperform annealing in a magnetic field. Therefore, the magnetoresistiveelements may be formed on the inclined side surfaces of the detectionrecesses in the same substrate so as to have any combination ofdirections of fixed magnetization (P).

What is claimed is:
 1. A magnetic detection device comprising: asubstrate having recesses, the substrate having a substrate surface anda thickness; and magnetoresistive elements provided on inclined sidesurfaces of the recesses, wherein the recesses each include a firstinclined side surface and a second inclined side surface opposing eachother with a distance therebetween gradually increasing toward asubstrate surface, the first inclined side surface and the secondinclined side surface having the magnetoresistive elements providedthereon, wherein the magnetoresistive elements each include a fixedmagnetic layer, a free magnetic layer, and a nonmagnetic intermediatelayer formed between the fixed magnetic layer and the free magneticlayer, wherein the fixed magnetic layer has a self-pinned structureincluding a first ferromagnetic layer, a second ferromagnetic layer incontact with the nonmagnetic intermediate layer, and an intermediatelayer disposed between the ferromagnetic layers, the first ferromagneticlayer and the second ferromagnetic layer having magnetization directionsfixed to antiparallel directions, wherein the magnetoresistive elementseach have a sensitivity axis determined by the magnetization directionof the second ferromagnetic layer, the sensitivity axis extending alonga corresponding one of the inclined side surfaces obliquely to athickness direction of the substrate, and a bridge circuit comprisingtwo element lines connected in parallel, each element line comprisingtwo of the magnetoresistive elements connected in series, the two of themagnetoresistive elements connected in series have the sensitivity axesoriented toward opposite sides in the thickness direction of thesubstrate.
 2. The magnetic detection device according to claim 1,wherein the magnetization directions of the first ferromagnetic layerand the second ferromagnetic layer of the fixed magnetic layer are setby layer formation in a magnetic field.
 3. The magnetic detection deviceaccording to claim 1, wherein the recesses include Z detection recessesdisposed at least at two locations on the substrate, and the bridgecircuit detects a magnetic field in a Z direction, the Z direction beingthe thickness direction of the substrate.
 4. The magnetic detectiondevice according to claim 3, wherein, in each of the Z detectionrecesses, the sensitivity axis of the magnetoresistive element providedon the first inclined side surface and the sensitivity axis of themagnetoresistive element provided on the second inclined side surfaceare oriented toward the opposite sides in the thickness direction of thesubstrate.
 5. The magnetic detection device according to claim 3,wherein the Z detection recesses include a Z detection recess in whichthe sensitivity axes of the magnetoresistive elements provided on thefirst inclined side surface and the second inclined side surface areboth oriented downward in the thickness direction of the substrate and aZ detection recess in which the sensitivity axes of the magnetoresistiveelements provided on the first inclined side surface and the secondinclined side surface are both oriented upward in the thicknessdirection of the substrate, wherein the magnetoresistive elementsprovided on the first inclined side surfaces of different ones of the Zdetection recesses and having the sensitivity axes oriented toward theopposite sides are connected in series to form a first element line,wherein the magnetoresistive elements provided on the second inclinedside surfaces of different ones of the Z detection recesses and havingthe sensitivity axes oriented toward the opposite sides are connected inseries to form a second element line, and wherein the first element lineand the second element line are connected in parallel to form the bridgecircuit.
 6. The magnetic detection device according to claim 3, whereinthe recesses include horizontal detection recesses disposed at least attwo locations in addition to the Z detection recesses, furthercomprising: a second bridge circuit comprising two element linesconnected in parallel, each element line comprising two of themagnetoresistive elements provided in the horizontal detection recessesconnected in series, the two of the magnetoresistive elements connectedin series having the sensitivity axes oriented toward opposite sidesalong the substrate surface, and wherein the second bridge circuitdetects a magnetic field in a direction parallel to the substratesurface.
 7. The magnetic detection device according to claim 6, wherein,in each of the horizontal detection recesses, the sensitivity axis ofthe magnetoresistive element provided on the first inclined side surfaceand the sensitivity axis of the magnetoresistive element provided on thesecond inclined side surface are oriented toward the opposite sidesalong the substrate surface.
 8. The magnetic detection device accordingto claim 6, wherein, in each of the horizontal detection recesses, thesensitivity axis of the magnetoresistive element provided on the firstinclined side surface and the sensitivity axis of the magnetoresistiveelement provided on the second inclined side surface are oriented towardthe same side along the substrate surface, wherein the sensitivity axesof the magnetoresistive elements provided in different ones of thehorizontal detection recesses are oriented toward the opposite sidesalong the substrate surface, wherein the magnetoresistive elementsprovided on the first inclined side surfaces of different ones of thehorizontal detection recesses and having the sensitivity axes orientedtoward the opposite sides are connected in series to form a firstelement line, wherein the magnetoresistive elements provided on thesecond inclined side surfaces of different ones of the horizontaldetection recesses and having the sensitivity axes oriented toward theopposite sides are connected in series to form a second element line,and wherein the first element line and the second element line areconnected in parallel to form the bridge circuit.
 9. The magneticdetection device according to claim 6, wherein the horizontal detectionrecesses include X detection recesses disposed at least at two locationson the substrate to detect a magnetic field in an X direction and Ydetection recesses disposed at least at two locations on the substrateto detect a magnetic field in a Y direction, the X and Y directionsbeing perpendicular to each other.
 10. A method for manufacturing amagnetic detection device including a substrate having recesses andmagnetoresistive elements provided on inclined side surfaces of therecesses, the method comprising: forming the recesses in the substrate,each recess including a first inclined side surface and a secondinclined side surface opposing each other with a distance therebetweengradually increasing toward a substrate surface; and forming themagnetoresistive elements on the first inclined side surface and thesecond inclined side surface of each recess, each magnetoresistiveelement including a fixed magnetic layer, a free magnetic layer, and anonmagnetic intermediate layer formed between the fixed magnetic layerand the free magnetic layer, wherein the fixed magnetic layer has aself-pinned structure including a first ferromagnetic layer, a secondferromagnetic layer in contact with the nonmagnetic intermediate layer,and an intermediate layer disposed between the ferromagnetic layers, thefirst ferromagnetic layer and the second ferromagnetic layer havingmagnetization directions fixed to antiparallel directions by layerformation in a magnetic field, wherein the magnetoresistive elementseach have a sensitivity axis determined by the magnetization directionof the second ferromagnetic layer, the sensitivity axis extending alonga corresponding one of the inclined side surfaces obliquely to athickness direction of the substrate, and wherein a bridge circuit isformed by connecting two element lines in parallel, each element linebeing formed by connecting in series two of the magnetoresistiveelements having the sensitivity axes oriented toward opposite sides inthe thickness direction of the substrate.
 11. The method formanufacturing the magnetic detection device according to claim 10,wherein the recesses include Z detection recesses formed at least at twolocations on the substrate, the magnetoresistive elements provided inthe Z detection recesses having the sensitivity axes oriented towarddifferent sides in the thickness direction of the substrate, wherein themagnetoresistive elements having the sensitivity axes oriented towardopposite sides in the thickness direction are connected in series toform the element lines, and wherein the bridge circuit is capable ofdetecting a magnetic field in a Z direction, the Z direction being thethickness direction of the substrate.
 12. The method for manufacturingthe magnetic detection device according to claim 11, wherein therecesses include horizontal detection recesses formed at least at twolocations on the substrate in addition to the Z detection recesses,wherein the magnetoresistive elements provided in the horizontaldetection recesses have the sensitivity axes oriented toward differentsides along the substrate surface, wherein the magnetoresistive elementshaving the sensitivity axes oriented toward opposite sides are connectedin series to form the element lines, and wherein the bridge circuit iscapable of detecting a magnetic field in a horizontal direction alongthe substrate surface of the substrate.
 13. The method for manufacturingthe magnetic detection device according to claim 12, wherein thehorizontal detection recesses include X detection recesses disposed atleast at two locations on the substrate to detect a magnetic field in anX direction and Y detection recesses disposed at least at two locationson the substrate to detect a magnetic field in a Y direction, the X andY directions being perpendicular to each other.